This study is an extension of the original placebo-controlled trial to determine the safety and efficacy of copolymer 1 in patients with relapsing-remitting multiple sclerosis. The controlled phase 3 trial showed that treatment with copolymer 1 was effective in reducing the clinical relapses and in slowing accumulated neurological disability compared to placebo treated patients. Most patients completing the phase 3 placebo controlled study elected to enroll in this open-labeled extension study of copolymer 1 for determination of long term safety and apparent persistence of efficacy. The study will be extended until April, 2000 with the evaluation of all enrolled patients with annual quantitative magnetic resonance imaging, with centralized image analysis conducted a the University of Texas-Houston Health Science Center.